On Wednesday, July 27, doctors and HIV researchers announced the fifth case of a patient being cured of HIV. The man is also the oldest person ever to be cured, and had lived with HIV since the 1980s.

A 66 year-old gay man, who doesn’t want to be identified and is referred to as the ‘City of Hope patient’ after the Californian cancer centre where he was treated, has become the fifth person to be cured of HIV. After developing leukemia at the age of 63, the man was given a bone marrow transplant to treat it from a donor who happened to be naturally resistant to HIV.

The HIV-resistant genetic abnormality that the donor had is seen in about 1% of people with northern European ancestry and it’s a mutation that keeps HIV out of the body’s white blood cells. The stem cell transplant allowed the new immune system from the donor to gradually overtake the old one in the fifth patient to be cured of HIV, making the man apparently viable-virus free.

Two years after the stem cell transplant, the man, in agreement with his physicians, decided to interrupt his antiretroviral treatment, which is considered effective treatment for people living with HIV. Ever since, he has remained viable-virus free, though the doctors and researchers working on his case will continue to monitor him and conduct further tests.

The man declared himself “beyond grateful” for being free from HIV. “When I was diagnosed with HIV in 1988, like many others, I thought it was a death sentence.” he said, “I never thought I would live to see the day that I no longer have HIV”.

Despite this success story, experts have talked about how using stem cell transplants to cure HIV is not ethical because it is a highly toxic and potentially fatal treatment usually reserved for people who have fatal blood cancer or similar health conditions. Moreover, such treatment offers no guarantees of success, as others have tried and failed to cure HIV using stem cell transplants in several cases.

The first case of a person cured of HIV is known as the Berlin case, which was announced in 2008. Then two more cases were announced in 2019 and became known as the London and the Düsseldorf patients. The fourth case of the New York patient, the first woman to be cured of HIV, was announced earlier this year.

Moreover, in January this year, the pharmaceutical giant Moderna announced that they had officially started Phase 1 of the trial to develop an HIV vaccine.